B.F. Goodrich Co., the tire maker turned aerospace company, said it will close four plants and eliminate 775 jobs, or 4.6% of its work force, as part of a cost-savings plan related to the 1997 acquisition of Rohr Inc. The company said it will take a fourth-quarter charge of about $7 million, or 9 cents a share, to pay for the moves, which it said will save about $10 million a year beginning in 2000. Richfield, Ohio-based Goodrich also said its profit for 1998 will exceed $3.04 a share, the average estimate of seven analysts polled by First Call Corp., before the charge. The plants to be closed, all acquired with Rohr, are in Maryland, Arkansas and Germany. Goodrich shares fell $2.94 to close at $34.75 on the NYSE.